Add new timezone for Hanoi Capital, Vietnam
These are the reasons that I think are reasonable - After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam - +7:00 (North Vietnam and All Vietnam since 1975) timezone has been the longest unified timezone ever, compared to Asia/Saigon, Asia/Ho_Chi_Minh (modified many times) I would like to suggest adding a timezone for Hanoi or changing the name from Asia/Ho_Chi_Minh to Asia/Hanoi as the official timezone for Vietnam. Having the same article should be considered https://tz.iana.narkive.com/foJrvdQn/tz-patch-tzdata-asia-ha-noi-add-new-tim...
KP wrote:
- After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam
tzdb goes by cities, not provinces. citypopulation.de estimates a population for Hanoi (including Ha Tay) that is less than that of Ho Chi Minh City. https://www.citypopulation.de/Vietnam-Cities.html gives 2017 estimates of 7.4 million for the former, and 8.4 million for the latter. Although both are growing, the ratio of Ho Chi Minh City vs Hanoi (including Ha Tay) population also appears to be growing, suggesting that Hanoi is not catching up. Even if Hanoi became somewhat larger than Ho Chi Minh City, the following guideline in <https://data.iana.org/time-zones/theory.html> would still apply: "Do not change established names if they only marginally violate the above guidelines. For example, do not change the existing name Europe/Rome to Europe/Milan merely because Milan's population has grown to be somewhat greater than Rome's."
- +7:00 (North Vietnam and All Vietnam since 1975) timezone has been the longest unified timezone ever
I'm not sure what's meant by "longest unified timezone ever". In tzdb, the location that has been at its current UT offset for the longest time is Atlantic/South_Georgia, unchanged since 1890. In contrast, tzdb's sources indicate that Hanoi changed UTC offset in 1954, which makes Hanoi less stable, time-wise, than Bangkok (last change 1920) or Lagos (last change 1919). At any rate, longevity of this sort has not been part of the criteria we've used to choose Zone names.
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970 and thus is already considered covered by the database. See https://mm.icann.org/pipermail/tz/2014-October/021669.html, and refer to the inclusion of "VN" in the following line of zone1970.tab: TH,KH,LA,VN +1345+10031 Asia/Bangkok Indochina (most areas) Though perhaps this warrants a brief comment in the "Vietnam" section of the asia file. -- Tim Parenti On Sun, 17 Feb 2019 at 20:43, Phake Nick <c933103@gmail.com> wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
Bringing Vietnam to Asia/Bangkok is unreasonable, if you ask the Vietnamese people, there will never be an "Yes" answer, since the feudal period so far, relations between Vietnam and Thailand Not good and especially Thai and Vietnamese are not a country, you will receive vehement feedback from the people of Vietnam. Vào 9:41, Th 2, 18 thg 2, 2019 Tim Parenti <tim@timtimeonline.com đã viết:
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970 and thus is already considered covered by the database. See https://mm.icann.org/pipermail/tz/2014-October/021669.html, and refer to the inclusion of "VN" in the following line of zone1970.tab:
TH,KH,LA,VN +1345+10031 Asia/Bangkok Indochina (most areas)
Though perhaps this warrants a brief comment in the "Vietnam" section of the asia file.
-- Tim Parenti
On Sun, 17 Feb 2019 at 20:43, Phake Nick <c933103@gmail.com> wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
On Feb 17, 2019, at 8:30 PM, KP <khaiphan9x@gmail.com> wrote:
Bringing Vietnam to Asia/Bangkok is unreasonable, if you ask the Vietnamese people, there will never be an "Yes" answer, since the feudal period so far, relations between Vietnam and Thailand Not good and especially Thai and Vietnamese are not a country, you will receive vehement feedback from the people of Vietnam.
Is it time to go with something less geographical (and thus less political/cultural/etc.) to identify tzdb regions? I guess if I had USD 1329.00 burning a hole in my pocket, I could buy the IANA "UTC/Local Time Comparisons": https://www.iata.org/publications/store/Documents/Passenger%20Standards/spec... and see what their two-character "Time Zone Code"s are, and whether they would correspond to tzdb regions. If so, maybe we could ask their permission to use them.
On Feb 17, 2019, at 6:40 PM, Tim Parenti <tim@timtimeonline.com> wrote:
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970
By which you presumably mean "from 1970 to 1976", because "pre-unification time" ends when North and South Vietnam were reunified in 1976.
and thus is already considered covered by the database.
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present. If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
Tz database does not deal with official timezone name. The time used in Vietnam being named Hanoi time doesn't make it more Hanoi than Ho Chi Minh as both should be using the same UTC+7 now. The different was in 1970s. If your software is expected to show official timezone name used in a region, then it's supposed to translate Asia/Ho_Chi_Minh into "Hanoi Time" On 2019-2-18 Mon 14:48, KP <khaiphan9x@gmail.com> wrote:
So, I mean, +7 is now more standard time with Hanoi than Ho Chi Minh City
----- The thing is, the timezone history of Hanoi and Ho Chi Minh look like this: Hanoi: 1970-2019 UTC+7 Ho Chi Minh: 1970-1975 UTC+8 1975-2019 UTC+7 Bangkok: 1970-2019 UTC+7 Thus you can see the timezone history of Hanoi match the timezone history of Bangkok from 1970 till now, while it doesn't match for HCM City. On 2019-2-18 Mon 16:53, Guy Harris <guy@alum.mit.edu> wrote:
On Feb 17, 2019, at 6:40 PM, Tim Parenti <tim@timtimeonline.com> wrote:
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970
By which you presumably mean "from 1970 to 1976", because "pre-unification time" ends when North and South Vietnam were reunified in 1976.
and thus is already considered covered by the database.
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
Thank you from the above friends, so you can see that the +7 time zone of Hanoi has a longer history and maybe 1 time zone is Asia/Hanoi. If you live in Vietnam, you will clearly see the difference in time in Hanoi and HCMC, in the future when Vietnam is more developed, it may be necessary to adjust the HN and HCMC timezone. Paul Eggert, I know that there must be some rules for forming time zones. However, I see many exceptions such as Shanghai and Beijing, there are many other places that I have not mentioned. I think Hanoi too full of criteria for a time zone, or you can consider it an exception. Why not? Vào 16:48, Th 2, 18 thg 2, 2019 Phake Nick <c933103@gmail.com đã viết:
Tz database does not deal with official timezone name. The time used in Vietnam being named Hanoi time doesn't make it more Hanoi than Ho Chi Minh as both should be using the same UTC+7 now. The different was in 1970s. If your software is expected to show official timezone name used in a region, then it's supposed to translate Asia/Ho_Chi_Minh into "Hanoi Time"
On 2019-2-18 Mon 14:48, KP <khaiphan9x@gmail.com> wrote:
So, I mean, +7 is now more standard time with Hanoi than Ho Chi Minh City
----- The thing is, the timezone history of Hanoi and Ho Chi Minh look like this: Hanoi: 1970-2019 UTC+7 Ho Chi Minh: 1970-1975 UTC+8 1975-2019 UTC+7 Bangkok: 1970-2019 UTC+7
Thus you can see the timezone history of Hanoi match the timezone history of Bangkok from 1970 till now, while it doesn't match for HCM City.
On 2019-2-18 Mon 16:53, Guy Harris <guy@alum.mit.edu> wrote:
On Feb 17, 2019, at 6:40 PM, Tim Parenti <tim@timtimeonline.com> wrote:
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970
By which you presumably mean "from 1970 to 1976", because "pre-unification time" ends when North and South Vietnam were reunified in 1976.
and thus is already considered covered by the database.
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
Could you explain what is the difference in time in Hanoi and HCMC you was referring to in the message? On 2019-2-18 Mon 18:21, KP <khaiphan9x@gmail.com> wrote:
Thank you from the above friends, so you can see that the +7 time zone of Hanoi has a longer history and maybe 1 time zone is Asia/Hanoi. If you live in Vietnam, you will clearly see the difference in time in Hanoi and HCMC, in the future when Vietnam is more developed, it may be necessary to adjust the HN and HCMC timezone. Paul Eggert, I know that there must be some rules for forming time zones. However, I see many exceptions such as Shanghai and Beijing, there are many other places that I have not mentioned. I think Hanoi too full of criteria for a time zone, or you can consider it an exception. Why not?
On Mon, 18 Feb 2019 at 05:21, KP <khaiphan9x@gmail.com> wrote:
Paul Eggert, I know that there must be some rules for forming time zones.
Those guidelines are well-established and are available in the theory.html file of our distribution. You can read the most recently-released version of that file here: ftp://ftp.iana.org/tz/tzdb-2018i/theory.html In particular, take note of these two guidelines: - "If all the clocks in a timezone have agreed since 1970, do not bother to include more than one timezone even if some of the clocks disagreed before 1970." - "Use the most populous among locations in a region, e.g., prefer Asia/Shanghai to Asia/Beijing." It is these two guidelines, and this group's generally strong adherence to them, that are the main reasons your request is meeting opposition.
However, I see many exceptions such as Shanghai and Beijing, there are many other places that I have not mentioned.
As many have mentioned repeatedly, and as is demonstrated by example in the guidelines quoted above, Asia/Beijing is NOT a zone that this database provides, and that is NOT an exception that this group has made. See these lines in the most recently-released 'asia' file, which you can see at ftp://ftp.iana.org/tz/tzdb-2018i/asia # Beijing time, used throughout China; represented by Shanghai. Zone Asia/Shanghai 8:05:43 - LMT 1901 8:00 Shang C%sT 1949 May 28 8:00 PRC C%sT Although the comment line acknowledges that the official governmental name of the time zone translates as "Beijing time", the actual name of the Zone for tz purposes is Asia/Shanghai. Both Shanghai and Beijing have always had the same clock offsets since 1970 (in this case, UT+8 with some DST from 1986 to 1991), so, by the first quoted guideline above, only one Zone is needed in the tz database. By the second quoted guideline above, Shanghai was chosen because it has a larger population than Beijing. If you are seeing Asia/Beijing as a time zone somewhere, then it is NOT coming directly from the data this group provides. You may find better luck petitioning the downstream distributor of that data, as it is NOT a valid example that will be found to be convincing here. * * * The case in Vietnam is indeed a little different, but it is already covered. Although clocks in Ho Chi Minh City and Hanoi HAVE differed since 1970 (by one hour until 1975-06-13), the clocks in Hanoi and Bangkok have not differed (that is, they have both been at UT+7 the whole time since 1970). So, by the first quoted guideline above, only one Zone is needed to represent both areas. By the second quoted guideline above, just like in the China case, Bangkok was chosen because it has a larger population than Hanoi: https://www.citypopulation.de/Thailand-Cities.html — Bangkok Metropolitan (15,931,300) https://www.citypopulation.de/Vietnam-Cities.html — Hà Nội including Hà Tây (7,420,100) By following the guidelines in theory.html, we find that Hanoi is already considered properly covered by Asia/Bangkok for all timestamps since 1970, and this is indeed already reflected by the inclusion of Vietnam's country code in the corresponding entry in the zone1970.tab file, which indicates that there are two options for Vietnam. You can see that file at ftp://ftp.iana.org/tz/tzdb-2018i/zone1970.tab TH,KH,LA,VN +1345+10031 Asia/Bangkok Indochina (most areas) ... VN +1045+10640 Asia/Ho_Chi_Minh Vietnam (south) Realistically, though, if you don't need timestamps from 1975 or earlier, then even Asia/Ho_Chi_Minh will work for those purposes. -- Tim Parenti
Dear KP, to summarize and perhaps resolve some confusion, I see two points here:
I would like to suggest adding a timezone for Hanoi or changing the name from Asia/Ho_Chi_Minh to Asia/Hanoi as the official timezone for Vietnam.
1) tzdb does not aim to provide or define a list of the current "official timezone" for any country. In contrast, it provides a list of official (and sometimes even inofficial?) time zones which have been valid for some certain area of the world from 1970 till now. Vietnam (VN) overlaps with two such areas (via zone1970.tab as Tim pointed out): one labeled "Asia/Ho_Chi_Minh" and one labeled "Asia/Bangkok", the latter covering a larger part of Indochina including Hanoi. Forming one single "official timezone" for Vietnam (or renaming "Asia/Ho_Chi_Minh" to "Asia/Hanoi") would not be correct, as from the 1970-based perspective of tzdb, the Ho Chi Minh area (South VN) and the Hanoi area (North VN) had different time zone rules (until 1975, as pointed out). So any system using tzdb data will require the implementer (or end user) to choose if either "Asia/Ho_Chi_Minh" or "Asia/Bangkok" should be used for any particular entered data, as it can make a difference for certain calculations, due to different time zone rules in the past. The special case here is that there are no more differences between South + North VN time zones since 1975. In contrast to countries with multiple time zones that are still differing today (e.g., Australia, Russia or the US), one can thus argue that a distinction between South + North VN time may not be practically relevant for many implementations, as it would only make a difference for data between 1970-1975. Any system implementer is free in offering end users a single "Vietnam time", which e.g., internally maps to tzdb's "Asia/Ho_Chi_Minh". However, this is up to any implementer and not to tzdb. 2) tzdb time zone names should rather be considered as (technical) identifiers. So "Asia/Bangkok" (and its links such as "Asia/Phnom_Penh") refer to the same set of time zone rules shared by that area. This is not imply any Thai influence or "leadership" regarding this time zone, but is a mere convention. If the Cambodian or Vietnamese government would deviate their time zone rules anytime soon, tzdb would automatically create separate identifiers - but only for "technical", not for political reasons! So tzdb's time zone "names" should not be taken too literal, as they do not intend to be used as user-facing labels. Software implementers can still apply localization and aliases on top of those identifiers. It's part of the truth though, that tzdb names might surface to end users at certain points. It's however not necessarily tzdb to blame for this. (Both points based on my current understand of the state of affairs - please feel free to correct me if I am wrong in some point) Best, Hans-Joerg On 18.02.19 11:21, KP wrote:
Thank you from the above friends, so you can see that the +7 time zone of Hanoi has a longer history and maybe 1 time zone is Asia/Hanoi. If you live in Vietnam, you will clearly see the difference in time in Hanoi and HCMC, in the future when Vietnam is more developed, it may be necessary to adjust the HN and HCMC timezone. Paul Eggert, I know that there must be some rules for forming time zones. However, I see many exceptions such as Shanghai and Beijing, there are many other places that I have not mentioned. I think Hanoi too full of criteria for a time zone, or you can consider it an exception. Why not?
Vào 16:48, Th 2, 18 thg 2, 2019 Phake Nick <c933103@gmail.com <mailto:c933103@gmail.com> đã viết:
Tz database does not deal with official timezone name. The time used in Vietnam being named Hanoi time doesn't make it more Hanoi than Ho Chi Minh as both should be using the same UTC+7 now. The different was in 1970s. If your software is expected to show official timezone name used in a region, then it's supposed to translate Asia/Ho_Chi_Minh into "Hanoi Time"
On 2019-2-18 Mon 14:48, KP <khaiphan9x@gmail.com <mailto:khaiphan9x@gmail.com>> wrote: >So, I mean, +7 is now more standard time with Hanoi than Ho Chi Minh City
----- The thing is, the timezone history of Hanoi and Ho Chi Minh look like this: Hanoi: 1970-2019 UTC+7 Ho Chi Minh: 1970-1975 UTC+8 1975-2019 UTC+7 Bangkok: 1970-2019 UTC+7
Thus you can see the timezone history of Hanoi match the timezone history of Bangkok from 1970 till now, while it doesn't match for HCM City.
On 2019-2-18 Mon 16:53, Guy Harris <guy@alum.mit.edu <mailto:guy@alum.mit.edu>> wrote:
On Feb 17, 2019, at 6:40 PM, Tim Parenti <tim@timtimeonline.com <mailto:tim@timtimeonline.com>> wrote:
> As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970
By which you presumably mean "from 1970 to 1976", because "pre-unification time" ends when North and South Vietnam were reunified in 1976.
> and thus is already considered covered by the database.
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
-- audriga GmbH Durlacher Allee 47 76131 Karlsruhe, Germany Tel: +49 (0) 721 17029 316 Fax: +49 (0) 721 17029 3179 www.twitter.com/audriga <http://www.twitter.com/audriga> www.audriga.com <http://www.audriga.com/> Handelsregister: Amtsgericht Mannheim - HRB 713034 Sitz der Gesellschaft: Karlsruhe Geschäftsführer: Dr. Frank Dengler, Dr. Hans-Jörg Happel USt-ID: DE 279724142
I will mention some of the following stages: - GMT+0: July 1, 1906 to April 30, 1911 (Indochina) - GMT+7: May 1, 1911 (Indochina) - GMT+8: 23:00 December 31, 1942 (Indochina) - GMT+9: 23:00 on March 14, 1945 (Empire of Vietnam) - GMT+7: September 2, 1945 (Democratic Republic of Vietnam) and July 1, 1955 (État du Viêt-Nam) - GMT+8: 23:00 on January 1, 1960 (Republic of Vietnam) and GMT+7: January 1968 (Democratic Republic of Vietnam) - GMT+7: June 13, 1975 (Republic of South Vietnam) Thus, Vietnam time has been different in 1945 (Saigon/HCMC does not exist) no longer in Indochina time. As mentioned, a small change can also lead to a timezone. It is possible to create a time zone for Hanoi from here according to the historical facts I mentioned. You can learn more documents to validate this information. Vào 2:43, Th 3, 19 thg 2, 2019 Hans-Joerg Happel <happel@audriga.com đã viết:
Dear KP,
to summarize and perhaps resolve some confusion, I see two points here:
I would like to suggest adding a timezone for Hanoi or changing the name from Asia/Ho_Chi_Minh to Asia/Hanoi as the official timezone for Vietnam.
1) tzdb does not aim to provide or define a list of the current "official timezone" for any country.
In contrast, it provides a list of official (and sometimes even inofficial?) time zones which have been valid for some certain area of the world from 1970 till now. Vietnam (VN) overlaps with two such areas (via zone1970.tab as Tim pointed out): one labeled "Asia/Ho_Chi_Minh" and one labeled "Asia/Bangkok", the latter covering a larger part of Indochina including Hanoi.
Forming one single "official timezone" for Vietnam (or renaming "Asia/Ho_Chi_Minh" to "Asia/Hanoi") would not be correct, as from the 1970-based perspective of tzdb, the Ho Chi Minh area (South VN) and the Hanoi area (North VN) had different time zone rules (until 1975, as pointed out).
So any system using tzdb data will require the implementer (or end user) to choose if either "Asia/Ho_Chi_Minh" or "Asia/Bangkok" should be used for any particular entered data, as it can make a difference for certain calculations, due to different time zone rules in the past.
The special case here is that there are no more differences between South + North VN time zones since 1975. In contrast to countries with multiple time zones that are still differing today (e.g., Australia, Russia or the US), one can thus argue that a distinction between South + North VN time may not be practically relevant for many implementations, as it would only make a difference for data between 1970-1975.
Any system implementer is free in offering end users a single "Vietnam time", which e.g., internally maps to tzdb's "Asia/Ho_Chi_Minh". However, this is up to any implementer and not to tzdb.
2) tzdb time zone names should rather be considered as (technical) identifiers. So "Asia/Bangkok" (and its links such as "Asia/Phnom_Penh") refer to the same set of time zone rules shared by that area.
This is not imply any Thai influence or "leadership" regarding this time zone, but is a mere convention. If the Cambodian or Vietnamese government would deviate their time zone rules anytime soon, tzdb would automatically create separate identifiers - but only for "technical", not for political reasons!
So tzdb's time zone "names" should not be taken too literal, as they do not intend to be used as user-facing labels. Software implementers can still apply localization and aliases on top of those identifiers.
It's part of the truth though, that tzdb names might surface to end users at certain points. It's however not necessarily tzdb to blame for this.
(Both points based on my current understand of the state of affairs - please feel free to correct me if I am wrong in some point)
Best, Hans-Joerg On 18.02.19 11:21, KP wrote:
Thank you from the above friends, so you can see that the +7 time zone of Hanoi has a longer history and maybe 1 time zone is Asia/Hanoi. If you live in Vietnam, you will clearly see the difference in time in Hanoi and HCMC, in the future when Vietnam is more developed, it may be necessary to adjust the HN and HCMC timezone. Paul Eggert, I know that there must be some rules for forming time zones. However, I see many exceptions such as Shanghai and Beijing, there are many other places that I have not mentioned. I think Hanoi too full of criteria for a time zone, or you can consider it an exception. Why not?
Vào 16:48, Th 2, 18 thg 2, 2019 Phake Nick <c933103@gmail.com đã viết:
Tz database does not deal with official timezone name. The time used in Vietnam being named Hanoi time doesn't make it more Hanoi than Ho Chi Minh as both should be using the same UTC+7 now. The different was in 1970s. If your software is expected to show official timezone name used in a region, then it's supposed to translate Asia/Ho_Chi_Minh into "Hanoi Time"
On 2019-2-18 Mon 14:48, KP <khaiphan9x@gmail.com> wrote:
So, I mean, +7 is now more standard time with Hanoi than Ho Chi Minh City
----- The thing is, the timezone history of Hanoi and Ho Chi Minh look like this: Hanoi: 1970-2019 UTC+7 Ho Chi Minh: 1970-1975 UTC+8 1975-2019 UTC+7 Bangkok: 1970-2019 UTC+7
Thus you can see the timezone history of Hanoi match the timezone history of Bangkok from 1970 till now, while it doesn't match for HCM City.
On 2019-2-18 Mon 16:53, Guy Harris <guy@alum.mit.edu> wrote:
On Feb 17, 2019, at 6:40 PM, Tim Parenti <tim@timtimeonline.com> wrote:
As was discussed on the original thread in October 2014, pre-unification time in Hanoi matches Asia/Bangkok since 1970
By which you presumably mean "from 1970 to 1976", because "pre-unification time" ends when North and South Vietnam were reunified in 1976.
and thus is already considered covered by the database.
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
-- audriga GmbH Durlacher Allee 47 76131 Karlsruhe, Germany Tel: +49 (0) 721 17029 316 Fax: +49 (0) 721 17029 3179 www.twitter.com/audrigawww.audriga.com
Handelsregister: Amtsgericht Mannheim - HRB 713034 Sitz der Gesellschaft: Karlsruhe Geschäftsführer: Dr. Frank Dengler, Dr. Hans-Jörg Happel USt-ID: DE 279724142
On Feb 18, 2019, at 12:31 PM, KP <khaiphan9x@gmail.com> wrote:
I will mention some of the following stages:
- GMT+0: July 1, 1906 to April 30, 1911 (Indochina)
- GMT+7: May 1, 1911 (Indochina)
- GMT+8: 23:00 December 31, 1942 (Indochina)
- GMT+9: 23:00 on March 14, 1945 (Empire of Vietnam)
- GMT+7: September 2, 1945 (Democratic Republic of Vietnam) and July 1, 1955 (État du Viêt-Nam)
- GMT+8: 23:00 on January 1, 1960 (Republic of Vietnam) and GMT+7: January 1968 (Democratic Republic of Vietnam)
All of those are outside the scope of the tzdb.
- GMT+7: June 13, 1975 (Republic of South Vietnam)
Thus, Vietnam time has been different in 1945 (Saigon/HCMC does not exist) no longer in Indochina time. As mentioned, a small change can also lead to a timezone. It is possible to create a time zone for Hanoi from here according to the historical facts I mentioned.
There *is*, in backzone, a tzdb region "Asia/Hanoi". It converts all times starting with 1970-01-01 00:00:00 UTC to local time in the same fashion as Asia/Bangkok. It converts times *prior* to 1970-01-01 00:00:00 UTC differently from Asia/Bangkok.
On Mon, 18 Feb 2019 at 15:32, KP <khaiphan9x@gmail.com> wrote:
Thus, Vietnam time has been different in 1945 (Saigon/HCMC does not exist) no longer in Indochina time. As mentioned, a small change can also lead to a timezone.
As has been pointed out before, we don't make new zones just because there are differences prior to 1970. Please read ftp://ftp.iana.org/tz/tzdb-2018i/theory.html and ensure you understand it. Ask if there is anything there you do not understand. On Mon, 18 Feb 2019 at 15:32, KP <khaiphan9x@gmail.com> wrote:
It is possible to create a time zone for Hanoi from here according to the historical facts I mentioned.
And that has already been done in the 'backzone' file, which can already be installed by those who require that level of detail. See ftp://ftp.iana.org/tz/tzdb-2018i/backzone: # Vietnam # From Paul Eggert (2014-10-13): # See Asia/Ho_Chi_Minh for the source for this data. # Trần's book says the 1954-55 transition to 07:00 in Hanoi was in # October 1954, with exact date and time unspecified. Zone Asia/Hanoi 7:03:24 - LMT 1906 Jul 1 7:06:30 - PLMT 1911 May 1 7:00 - +07 1942 Dec 31 23:00 8:00 - +08 1945 Mar 14 23:00 9:00 - +09 1945 Sep 2 7:00 - +07 1947 Apr 1 8:00 - +08 1954 Oct 7:00 - +07 The ONLY question that remains open here is whether Asia/Hanoi should be moved into the mainstream distribution. As you will have seen from this discussion, there are several reasons for and against such a proposal, and those will require thoughtful discussion. Further arguments will not strengthen your case beyond that. -- Tim Parenti
On Tue 2019-02-19T03:31:45+0700 KP hath writ:
- GMT+0: July 1, 1906 to April 30, 1911 (Indochina) - GMT+7: May 1, 1911 (Indochina) - GMT+8: 23:00 December 31, 1942 (Indochina) - GMT+9: 23:00 on March 14, 1945 (Empire of Vietnam) - GMT+7: September 2, 1945 (Democratic Republic of Vietnam) and July 1,
BIH Bulletin Horaire indicates that Saigon was transmitting time signals in 1924 and beginning with 1925 their reception times are tabulated. An interesting note in Series 1 number 2 page 1 is that there was only one transmitter so starting 1941-12-08 Saigon sacrificed time signals for more important traffic. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m
On Mon, 18 Feb 2019 at 03:53, Guy Harris <guy@alum.mit.edu> wrote:
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
To be a bit more precise, for our purposes, I mean when the *clocks* were reunified, independent from the various stages of political reunification. Our data has that occurring on 1975-06-13. Since that time, all of Vietnam has agreed with Asia/Bangkok, so there is no issue there.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
This, however, is where the need for a second zone for Vietnam arises. And indeed there are already two listed in zone1970.tab (Asia/Ho_Chi_Minh and Asia/Bangkok); it's just that one of them happens to be modeled by a city outside Vietnam. That is not considered a problem per theory.html. -- Tim Parenti
On 2019-2-18 Mon 22:42, Tim Parenti <tim@timtimeonline.com> wrote:
On Mon, 18 Feb 2019 at 03:53, Guy Harris <guy@alum.mit.edu> wrote:
If *post*-unification time - which is post-1970 - doesn't match Asia/Bangkok, then Asia/Bangkok should not be used for any part of Vietnam; there should be one or more Asia/{whatever} for Vietnam from 1970 to the present.
To be a bit more precise, for our purposes, I mean when the *clocks* were reunified, independent from the various stages of political reunification. Our data has that occurring on 1975-06-13. Since that time, all of Vietnam has agreed with Asia/Bangkok, so there is no issue there.
If Vietnam's pre-unification offset or rules were different between the north and the south from 1970 to 1976, then "one or more" means "at least two", e.g. Asia/Hanoi and Asia/Ho_Chi_Minh (even if it was called Saigon in 1970).
This, however, is where the need for a second zone for Vietnam arises. And indeed there are already two listed in zone1970.tab (Asia/Ho_Chi_Minh and Asia/Bangkok); it's just that one of them happens to be modeled by a city outside Vietnam. That is not considered a problem per theory.html.
-- Tim Parenti
Also pay attention that, because it is the time history of Ho Chi Minh city not time history of South Vietnam, the rule represent the transition of clock due to change in political status of the city as the city was being captured by Northern Vietnam. Southern Vietnam might still control some other territories and use their own clock thereafter but those are not part of time history of HCM City and are thus not recorded here.
On Mon, 18 Feb 2019 at 10:03, Phake Nick <c933103@gmail.com> wrote:
Also pay attention that, because it is the time history of Ho Chi Minh city not time history of South Vietnam, the rule represent the transition of clock due to change in political status of the city as the city was being captured by Northern Vietnam.
Another very good point — and one that's easy to miss! — which should probably also be added to the commentary in the file. -- Tim Parenti
Tim Parenti said:
Also pay attention that, because it is the time history of Ho Chi Minh city not time history of South Vietnam, the rule represent the transition of clock due to change in political status of the city as the city was being captured by Northern Vietnam. Another very good point ??? and one that's easy to miss! ??? which should probably also be added to the commentary in the file.
Hmm, do we need another zone for that? Or will there be a string of such zones as the border moved south? I don't know the history of Vietnam well enough to know. -- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
A country may not have a representative time zone (borrow another country). The standards seem to have been broken, very unreasonable, I think it is working according to the arrangement rather than the rules. Today countries can have one or more separate time zones, according to your inference, Jakarta of Indonesia has the largest area and population, inferred, all countries have +7:00 timezones in the neighborhoods must use Asia/Jakarta. Countries including Cambodia, Laos and South Vietnam (regardless of agreement) have their own time zones, except North Vietnam. Is it an omission or bias? Vào 22:13, Th 2, 18 thg 2, 2019 Clive D.W. Feather <clive@davros.org đã viết:
Tim Parenti said:
Also pay attention that, because it is the time history of Ho Chi Minh city not time history of South Vietnam, the rule represent the transition of clock due to change in political status of the city as the city was being captured by Northern Vietnam. Another very good point ??? and one that's easy to miss! ??? which should probably also be added to the commentary in the file.
Hmm, do we need another zone for that? Or will there be a string of such zones as the border moved south? I don't know the history of Vietnam well enough to know.
-- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
Rules are too confusing or like "Law of the Jungle" Vào 23:37, Th 2, 18 thg 2, 2019 KP <khaiphan9x@gmail.com đã viết:
A country may not have a representative time zone (borrow another country). The standards seem to have been broken, very unreasonable, I think it is working according to the arrangement rather than the rules. Today countries can have one or more separate time zones, according to your inference, Jakarta of Indonesia has the largest area and population, inferred, all countries have +7:00 timezones in the neighborhoods must use Asia/Jakarta. Countries including Cambodia, Laos and South Vietnam (regardless of agreement) have their own time zones, except North Vietnam. Is it an omission or bias?
Vào 22:13, Th 2, 18 thg 2, 2019 Clive D.W. Feather <clive@davros.org đã viết:
Tim Parenti said:
Also pay attention that, because it is the time history of Ho Chi Minh city not time history of South Vietnam, the rule represent the transition of clock due to change in political status of the city as the city was being captured by Northern Vietnam. Another very good point ??? and one that's easy to miss! ??? which should probably also be added to the commentary in the file.
Hmm, do we need another zone for that? Or will there be a string of such zones as the border moved south? I don't know the history of Vietnam well enough to know.
-- Clive D.W. Feather | If you lie to the compiler, Email: clive@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646
On 18/02/2019 16:40, KP wrote:
Rules are too confusing or like "Law of the Jungle" Added to which, there is a lottery as to just what one gets prior to 1970 anyway. If there ARE documented differences in the pre-1970 sequences for a location, then it should be documented, but in many cases it is simply the latitude which provides the base time offset for the whole of that strip of the world independent of any politics. Locations should not be thought of a each having their own timezone, but rather using a set of rules for a period of time. That rules have 'location' related tags has been a problem since day one, and the fact that user interfaces insist on using those tags DESPITE the rule about not doing so does not help and is no reason for adding more locations.
-- Lester Caine - G8HFL ----------------------------- Contact - https://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - https://lsces.co.uk EnquirySolve - https://enquirysolve.com/ Model Engineers Digital Workshop - https://medw.co.uk Rainbow Digital Media - https://rainbowdigitalmedia.co.uk
On Mon, 18 Feb 2019 at 11:37, KP <khaiphan9x@gmail.com> wrote:
Countries including Cambodia, Laos and South Vietnam (regardless of agreement) have their own time zones, except North Vietnam. Is it an omission or bias?
Not really. Cambodia and Laos are linked to Asia/Bangkok as well: # Thailand # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Bangkok 6:42:04 - LMT 1880 6:42:04 - BMT 1920 Apr # Bangkok Mean Time 7:00 - +07 Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos That said, it does look like Asia/Hanoi (which currently exists in the backzone file) should indeed be linked here as well for the same reasons, since Asia/Ho_Chi_Minh does differ from these from 1970 to 1975. It would appear that was an oversight due to the various complexities. Commentary should also be added in the Vietnam section of the file, if the link isn't added there. Or perhaps this is indeed a complex enough case to warrant bringing Asia/Hanoi out of backzone. Either way, the name should be in the main distribution somewhere, since Asia/Ho_Chi_Minh is not representative of Vietnam alone. On Mon, 18 Feb 2019 at 10:13, Clive D.W. Feather <clive@davros.org> wrote:
Hmm, do we need another zone for that? Or will there be a string of such zones as the border moved south? I don't know the history of Vietnam well enough to know.
I should hope that in post-1970 cases of incremental territorial shifts, we can treat this a bit like we treat Asia/Urumqi: The geographical boundaries are/were fluid/undefined, and you simply choose the file that adheres to whichever timescale is most appropriate for your situation. The line between limiting ourselves to the two "major" zones and creating a new zone for each city as it was captured may be fuzzy, but I'm pretty confident that line exists somewhere in there. -- Tim Parenti
It is possible to link Hanoi to Asia/Ho_Chi_Minh instead of Asia/Bangkok as the logic you say will be better. The above-mentioned criteria seem to be ignored, although it is quite reasonable. North Vietnam uses time zones imposed, there is no document saying that North Vietnam accepted Asia/Bangkok as a representative time zone. However, I did not change the idea that Hanoi is the best representative for Vietnam, although I do not have the right to change anything. Vào 23:52, Th 2, 18 thg 2, 2019 Tim Parenti <tim@timtimeonline.com đã viết:
On Mon, 18 Feb 2019 at 11:37, KP <khaiphan9x@gmail.com> wrote:
Countries including Cambodia, Laos and South Vietnam (regardless of agreement) have their own time zones, except North Vietnam. Is it an omission or bias?
Not really. Cambodia and Laos are linked to Asia/Bangkok as well:
# Thailand # Zone NAME GMTOFF RULES FORMAT [UNTIL] Zone Asia/Bangkok 6:42:04 - LMT 1880 6:42:04 - BMT 1920 Apr # Bangkok Mean Time 7:00 - +07 Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos
That said, it does look like Asia/Hanoi (which currently exists in the backzone file) should indeed be linked here as well for the same reasons, since Asia/Ho_Chi_Minh does differ from these from 1970 to 1975. It would appear that was an oversight due to the various complexities.
Commentary should also be added in the Vietnam section of the file, if the link isn't added there. Or perhaps this is indeed a complex enough case to warrant bringing Asia/Hanoi out of backzone. Either way, the name should be in the main distribution somewhere, since Asia/Ho_Chi_Minh is not representative of Vietnam alone.
On Mon, 18 Feb 2019 at 10:13, Clive D.W. Feather <clive@davros.org> wrote:
Hmm, do we need another zone for that? Or will there be a string of such zones as the border moved south? I don't know the history of Vietnam well enough to know.
I should hope that in post-1970 cases of incremental territorial shifts, we can treat this a bit like we treat Asia/Urumqi: The geographical boundaries are/were fluid/undefined, and you simply choose the file that adheres to whichever timescale is most appropriate for your situation. The line between limiting ourselves to the two "major" zones and creating a new zone for each city as it was captured may be fuzzy, but I'm pretty confident that line exists somewhere in there.
-- Tim Parenti
On Mon, 18 Feb 2019 at 12:07, KP <khaiphan9x@gmail.com> wrote:
there is no document saying that North Vietnam accepted Asia/Bangkok as a representative time zone
There does not need to be such a document, as we're not aiming to reflect "acceptance" of anything. All our data would assert is that Hanoi's clocks have matched Bangkok's since 1970. It could just as easily be said that Bangkok's clocks have matched Hanoi's for the same period; the two statements are equivalent. It doesn't matter to us whether this is due to cooperation, coercion, or coincidence. The direction of the link in our data would simply be based on the relative populations, and Bangkok is the larger city. -- Tim Parenti
I know that all my similar ideas will not be accepted, so I will not say more until I have an extremely convincing opinion. And I also want to ask why so many time zones do not comply rules and do not need to be created, certainly the future will repeat the same thing. Vào 0:21, Th 3, 19 thg 2, 2019 Tim Parenti <tim@timtimeonline.com đã viết:
On Mon, 18 Feb 2019 at 12:07, KP <khaiphan9x@gmail.com> wrote:
there is no document saying that North Vietnam accepted Asia/Bangkok as a representative time zone
There does not need to be such a document, as we're not aiming to reflect "acceptance" of anything. All our data would assert is that Hanoi's clocks have matched Bangkok's since 1970. It could just as easily be said that Bangkok's clocks have matched Hanoi's for the same period; the two statements are equivalent. It doesn't matter to us whether this is due to cooperation, coercion, or coincidence.
The direction of the link in our data would simply be based on the relative populations, and Bangkok is the larger city.
-- Tim Parenti
On Feb 18, 2019, at 9:07 AM, KP <khaiphan9x@gmail.com> wrote:
It is possible to link Hanoi to Asia/Ho_Chi_Minh instead of Asia/Bangkok
...but doing so means that pre-time-zone-unification but post-1970-01-01 00:00:00 UTC dates will not be converted correctly, so it would be incorrect to do so.
there is no document saying that North Vietnam accepted Asia/Bangkok as a representative time zone.
What matters isn't whether they officially accepted it; what matters is whether they, in practice, kept the same time.
However, I did not change the idea that Hanoi is the best representative for Vietnam,
Given that there are, apparently, post-1970-01-01 00:00:00 UTC dates/times where local time differed between locations in what was then North Vietnam and what was then South Vietnam, there isn't a single tzdb region that represents Vietnam, there are two.
I have a talent for continuous change of Indochina time, but it is a Vietnamese document, I have not found the same document in English. Show that the time of Vietnam taking Asia/Bangkok is wrong, because Thai does not apply under this document https://vi.m.wikipedia.org/wiki/Giờ_ở_Việt_Nam Vào 0:59, Th 3, 19 thg 2, 2019 Guy Harris <guy@alum.mit.edu đã viết:
On Feb 18, 2019, at 9:07 AM, KP <khaiphan9x@gmail.com> wrote:
It is possible to link Hanoi to Asia/Ho_Chi_Minh instead of Asia/Bangkok
...but doing so means that pre-time-zone-unification but post-1970-01-01 00:00:00 UTC dates will not be converted correctly, so it would be incorrect to do so.
there is no document saying that North Vietnam accepted Asia/Bangkok as a representative time zone.
What matters isn't whether they officially accepted it; what matters is whether they, in practice, kept the same time.
However, I did not change the idea that Hanoi is the best representative for Vietnam,
Given that there are, apparently, post-1970-01-01 00:00:00 UTC dates/times where local time differed between locations in what was then North Vietnam and what was then South Vietnam, there isn't a single tzdb region that represents Vietnam, there are two.
On Feb 18, 2019, at 10:07 AM, KP <khaiphan9x@gmail.com> wrote:
I have a talent for continuous change of Indochina time, but it is a Vietnamese document, I have not found the same document in English. Show that the time of Vietnam taking Asia/Bangkok is wrong, because Thai does not apply under this document https://vi.m.wikipedia.org/wiki/Giờ_ở_Việt_Nam
See https://translate.google.com/translate?sl=auto&tl=en&u=https%3A%2F%2Fvi.wikipedia.org%2Fwiki%2FGiờ_ở_Việt_Nam for the Google translation into English. What it says about post-1970-01-01 00:00:00 UTC times is: Time in Northern Vietnam ... January 1, 1968 - June 12, 1975 UTC + 07:00:00 Hanoi time zone Time in South Vietnam ... January 1, 1960 - June 12, 1975 UTC + 8:00 pm Saigon Standard Time The time in Vietnam is unified June 13, 1975 -nay UTC + 07:00:00 Standard time zone with no indication about standard vs. summer time; the tzdb doesn't show Vietnam ever having seasonal time shifts, so that makes sense. The only reference given on the page doesn't seem to, in the generated translation, address time zones at all. And, no, it says nothing about Thailand, but, as noted, North Vietnam happened to keep the same time as Thailand from 1970 to reunification; *that's*, plus Bangkok being larger than Hanoi, why Asia/Bangkok is used as the tzdb id for that region.
On 2/18/19 10:07 AM, KP wrote:
https://vi.m.wikipedia.org/wiki/Giờ_ở_Việt_Nam <https://vi.m.wikipedia.org/wiki/Gi%E1%BB%9D_%E1%BB%9F_Vi%E1%BB%87t_Nam>
This cites the same source that we've used for our Vietnam data. If the web page contains other information that would be relevant to tzdb, please let us know. The source is cited in the 'asia' file as follows: # Trần Tiến Bình's authoritative book "Lịch Việt Nam: thế kỷ XX-XXI (1901-2100)" # (Nhà xuất bản Văn Hoá - Thông Tin, Hanoi, 2005), pp 49-50, # is quoted verbatim in: # http://www.thoigian.com.vn/?mPage=P80D01 # is translated by Brian Inglis in: # https://mm.icann.org/pipermail/tz/2014-October/021654.html # and is the basis for the information below. I checked a printed copy of Trần's book and verified that the thoigian.com.vn quote is verbatim. WorldCat says there's another version of Trần's book dated 2013: https://www.worldcat.org/oclc/946663040 However, WorldCat lists only two copies of this version in the world's libraries (one in the Library of Congress, the other in the Bibliothèque nationale de France). Also, there's a good chance that the WorldCat listing is in error, or that the 2013 edition's updates (if any) don't affect tzdb. So I haven't investigated this.
On 2019-02-19 10:56, Paul Eggert wrote:
On 2/18/19 10:07 AM, KP wrote:
https://vi.m.wikipedia.org/wiki/Giờ_ở_Việt_Nam <https://vi.m.wikipedia.org/wiki/Gi%E1%BB%9D_%E1%BB%9F_Vi%E1%BB%87t_Nam> This cites the same source that we've used for our Vietnam data. If the web page contains other information that would be relevant to tzdb, please let us know. The source is cited in the 'asia' file as follows: # Trần Tiến Bình's authoritative book "Lịch Việt Nam: thế kỷ XX-XXI (1901-2100)" # (Nhà xuất bản Văn Hoá - Thông Tin, Hanoi, 2005), pp 49-50, # is quoted verbatim in: # http://www.thoigian.com.vn/?mPage=P80D01 # is translated by Brian Inglis in: # https://mm.icann.org/pipermail/tz/2014-October/021654.html # and is the basis for the information below. I checked a printed copy of Trần's book and verified that the thoigian.com.vn quote is verbatim. WorldCat says there's another version of Trần's book dated 2013: https://www.worldcat.org/oclc/946663040 However, WorldCat lists only two copies of this version in the world's libraries (one in the Library of Congress, the other in the Bibliothèque nationale de France). Also, there's a good chance that the WorldCat listing is in error, or that the 2013 edition's updates (if any) don't affect tzdb. So I haven't investigated this.
Suspicious that the National Library of Vietnam does not catalogue a copy, although the colonial interests BN and LoC do. Any chance that a national of those countries could ask their national library for a copy of the title/subtitle/copyright pages and those pages with the headings in the online quotation? -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
On Feb 18, 2019, at 6:41 AM, Tim Parenti <tim@timtimeonline.com> wrote:
This, however, is where the need for a second zone for Vietnam arises. And indeed there are already two listed in zone1970.tab (Asia/Ho_Chi_Minh and Asia/Bangkok);
So Hanoi time has always had the same offset same as Bangkok time from 1970-01-01 00:00:00 UTC to the present, and, like Bangkok, has never had summer time/DST? If so, then is the reason that we have Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos but don't have, for example, Link Asia/Bangkok Asia/Hanoi # (North) Vietnam that Asia/Phnom_Penh and Asia/Vientiane existed as separate entries before being combined with Asia/Bangkok, so that we need to keep their entire around for backwards compatibility, but there had never been an Asia/Hanoi?
On Mon, 18 Feb 2019 at 12:23, Guy Harris <guy@alum.mit.edu> wrote:
If so, then is the reason that we have
Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos
but don't have, for example,
Link Asia/Bangkok Asia/Hanoi # (North) Vietnam
that Asia/Phnom_Penh and Asia/Vientiane existed as separate entries before being combined with Asia/Bangkok, so that we need to keep their entire around for backwards compatibility, but there had never been an Asia/Hanoi?
It looks like that's indeed what happened. Thanks for jogging my memory. So I guess it wasn't an omission so much as an awkward and poorly-documented decision: - Asia/Phnom_Penh and Asia/Vientiane (which had existed prior) were combined with Asia/Bangkok on 2014-10-04 in https://github.com/eggert/tz/commit/6f7ddecfb036e13a1132181cfaa8ab3e070fc9e8 - Asia/Hanoi (which had NOT existed prior) was added to backzone on 2014-10-11 in https://github.com/eggert/tz/commit/bcb616ca405583de10e6e8c85951720ef066877a If we had known about the differences in Asia/Hanoi at least one release prior to this merging (and I recall all of this came up as part of the same discussion), then Asia/Hanoi would have needed to become a separate zone at that time. But because we first took the opportunity to coalesce the other zones, Asia/Hanoi's history could be coalesced as well, which is why it landed only in 'backzone' and not in 'asia'. I do think this boils down to a judgement call, though. There certainly could be an appearance of bias (though none was intended, it simply wasn't necessary to include Asia/Hanoi for backwards compatibility as it hadn't yet existed). Given that and the other complexities here, I would personally be inclined to move the Asia/Hanoi into the mainstream distribution, but I can absolutely see how others involved in the maintenance here may disagree. At the very least, better documentation in the 'asia' file is a pretty clear must. -- Tim Parenti
Timezones used in Vietnam are +7:00, +8:00, +9:00 instead of +7:00 only like Bangkok, Thailand Vào 1:19, Th 3, 19 thg 2, 2019 Guy Harris <guy@alum.mit.edu đã viết:
On Feb 18, 2019, at 6:41 AM, Tim Parenti <tim@timtimeonline.com> wrote:
This, however, is where the need for a second zone for Vietnam arises. And indeed there are already two listed in zone1970.tab (Asia/Ho_Chi_Minh and Asia/Bangkok);
So Hanoi time has always had the same offset same as Bangkok time from 1970-01-01 00:00:00 UTC to the present, and, like Bangkok, has never had summer time/DST?
If so, then is the reason that we have
Link Asia/Bangkok Asia/Phnom_Penh # Cambodia Link Asia/Bangkok Asia/Vientiane # Laos
but don't have, for example,
Link Asia/Bangkok Asia/Hanoi # (North) Vietnam
that Asia/Phnom_Penh and Asia/Vientiane existed as separate entries before being combined with Asia/Bangkok, so that we need to keep their entire around for backwards compatibility, but there had never been an Asia/Hanoi?
Why is Bangkok's time taken from 1920, but Hanoi's time is only taken from 1970? Vào 2:19, Th 3, 19 thg 2, 2019 Guy Harris <guy@alum.mit.edu đã viết:
On Feb 18, 2019, at 10:22 AM, KP <khaiphan9x@gmail.com> wrote:
Timezones used in Vietnam are +7:00, +8:00, +9:00 instead of +7:00 only like Bangkok, Thailand
...prior to 1970-01-01 00:00:00. That's why Asia/Hanoi is in backzone rather than asia.
On Feb 18, 2019, at 11:27 AM, KP <khaiphan9x@gmail.com> wrote:
Why is Bangkok's time taken from 1920, but Hanoi's time is only taken from 1970?
To quote the theory page: It organizes time zone and daylight saving time data by partitioning the world into timezones whose clocks all agree about timestamps that occur after the POSIX Epoch (1970-01-01 00:00:00 UTC). ... Clock transitions before 1970 are recorded for each timezone, because most systems support timestamps before 1970 and could misbehave if data entries were omitted for pre-1970 transitions. However, the database is not designed for and does not suffice for applications requiring accurate handling of all past times everywhere, as it would take far too much effort and guesswork to record all details of pre-1970 civil timekeeping. Although some information outside the scope of the database is collected in a file backzone that is distributed along with the database proper, this file is less reliable and does not necessarily follow database guidelines. ... * Use the most populous among locations in a region, e.g., prefer Asia/Shanghai to Asia/Beijing. Among locations with similar populations, pick the best-known location, e.g., prefer Europe/Rome to Europe/Milan. The first of those means that the tzdb region ("timezone") that includes Bangkok also includes Hanoi, as clocks in Thailand and the northern part of Vietnam agree about timestamps that occur after the POSIX Epoch, even though they disagree about time zones that occur before it. The second of those means that the entry for that region must have *something* for times prior to the Epoch, even if it's not accurate for all of that region prior to the Epoch, and even if it's not accurate for *any* of that region due to the "effort and guesswork" needed to get it to be accurate not being done, and that some information might still be available in the backzone file - which it is, for Vietnam: # Vietnam # From Paul Eggert (2014-10-13): # See Asia/Ho_Chi_Minh for the source for this data. # Trần's book says the 1954-55 transition to 07:00 in Hanoi was ins. # October 1954, with exact date and time unspecified. Zone Asia/Hanoi 7:03:24 - LMT 1906 Jul 1 7:06:30 - PLMT 1911 May 1 7:00 - +07 1942 Dec 31 23:00 8:00 - +08 1945 Mar 14 23:00 9:00 - +09 1945 Sep 2 7:00 - +07 1947 Apr 1 8:00 - +08 1954 Oct 7:00 - +07 The third of those means that the name chosen for that zone is Asia/Bangkok rather than Asia/Hanoi, so it has pre-Epoch data for Thailand rather than Vietnam.
On 2/17/19 6:40 PM, Tim Parenti wrote:
perhaps this warrants a brief comment in the "Vietnam" section of the asia file.
Good idea. A proposed patch is attached. This patch also attempts to address the issue of whether we should add a separate zone whenever any hamlet was taken by one side or the other during the 1970-1975 war in Vietnam, a topic you mentioned in a later email.
On Feb 17, 2019, at 5:43 PM, Phake Nick <c933103@gmail.com> wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
Any references for what differed between the two regions?
Southern Vietnan was using UTC+8 during that period while Northern Vietnam was using UTC+7 On 2019-2-18 Mon 13:09, Guy Harris <guy@alum.mit.edu> wrote:
On Feb 17, 2019, at 5:43 PM, Phake Nick <c933103@gmail.com> wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
Any references for what differed between the two regions?
So, I mean, +7 is now more standard time with Hanoi than Ho Chi Minh City Vào 13:17, Th 2, 18 thg 2, 2019 Phake Nick <c933103@gmail.com đã viết:
Southern Vietnan was using UTC+8 during that period while Northern Vietnam was using UTC+7
On 2019-2-18 Mon 13:09, Guy Harris <guy@alum.mit.edu> wrote:
On Feb 17, 2019, at 5:43 PM, Phake Nick <c933103@gmail.com> wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected.
Any references for what differed between the two regions?
On 2019-02-17 21:40, Guy Harris wrote:
On Feb 17, 2019, at 5:43 PM, Phake Nick wrote:
It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected. Any references for what differed between the two regions?
Vietnamese references used for previous consideration of Ha Noi: https://mm.icann.org/pipermail/tz/2014-October/021633.html It would be useful if anyone could provide links or references to available sources (and translations) that would update the record. The original sources referenced in the online summary linked from the thread above were not available. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
On Sun, Feb 17, 2019 at 8:50 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
KP wrote:
- After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam
tzdb goes by cities, not provinces. citypopulation.de estimates a population for Hanoi (including Ha Tay) that is less than that of Ho Chi Minh City. https://www.citypopulation.de/Vietnam-Cities.html gives 2017 estimates of 7.4 million for the former, and 8.4 million for the latter. Although both are growing, the ratio of Ho Chi Minh City vs Hanoi (including Ha Tay) population also appears to be growing, suggesting that Hanoi is not catching up.
By populations... % ls /usr/share/zoneinfo/America/|wc -l 144 % ls /usr/share/zoneinfo/Asia/|wc -l 99 Asia has around 59% of the world's population in 48 countries; the Americas have 14% in 35 countries. Seems quite possible there's scope to improve things in Asia. Kevin -- Kevin Lyda Galway, Ireland
Perhaps national government intervention is needed for this time zone issue Vào 12:47, Th 3, 19 thg 2, 2019 Kevin Lyda <kevin@ie.suberic.net đã viết:
On Sun, Feb 17, 2019 at 8:50 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
KP wrote:
- After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam
tzdb goes by cities, not provinces. citypopulation.de estimates a population for Hanoi (including Ha Tay) that is less than that of Ho Chi Minh City. https://www.citypopulation.de/Vietnam-Cities.html gives 2017 estimates of 7.4 million for the former, and 8.4 million for the latter. Although both are growing, the ratio of Ho Chi Minh City vs Hanoi (including Ha Tay) population also appears to be growing, suggesting that Hanoi is not catching up.
By populations...
% ls /usr/share/zoneinfo/America/|wc -l 144 % ls /usr/share/zoneinfo/Asia/|wc -l 99
Asia has around 59% of the world's population in 48 countries; the Americas have 14% in 35 countries. Seems quite possible there's scope to improve things in Asia.
Kevin
-- Kevin Lyda Galway, Ireland
On 2019-02-19 00:31, KP wrote:
Vào 12:47, Th 3, 19 thg 2, 2019 Kevin Lyda đã viết: On Sun, Feb 17, 2019 at 8:50 PM Paul Eggert wrote:
KP wrote:
- After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam tzdb goes by cities, not provinces. citypopulation.de <http://citypopulation.de> estimates a population for Hanoi (including Ha Tay) that is less than that of Ho Chi Minh City. https://www.citypopulation.de/Vietnam-Cities.html gives 2017 estimates of 7.4 million for the former, and 8.4 million for the latter. Although both are growing, the ratio of Ho Chi Minh City vs Hanoi (including Ha Tay) population also appears to be growing, suggesting that Hanoi is not catching up. By populations... % ls /usr/share/zoneinfo/America/|wc -l 144 % ls /usr/share/zoneinfo/Asia/|wc -l 99 Asia has around 59% of the world's population in 48 countries; the Americas have 14% in 35 countries. Seems quite possible there's scope to improve things in Asia.
Perhaps national government intervention is needed for this time zone issue
Involvement in providing timely information, and historical background *with references and translations*, would be better. Otherwise you could see current changes in contentious areas, argued about for weeks or months, by parties with political stakes, before being approved. In which case a group like this would still have to handle the practical matter of getting timely changes distributed instead of arguing about politics. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
Date: Tue, 19 Feb 2019 14:31:12 +0700 From: KP <khaiphan9x@gmail.com> Message-ID: <CAN9+tTtZAXwjZEbG1osoM4sjqyfUe0fHPpBFnGW+A60ZwAKKsA@mail.gmail.com> | Perhaps national government intervention is needed for this time zone issue You could request that they change Hanoi's time (offset from UTC). That's about the only thing that is likely to make much of a significant change. It seems like a kind of drastic measure for what is really a vanity issue. kre
On Feb 18, 2019, at 9:47 PM, Kevin Lyda <kevin@ie.suberic.net> wrote:
By populations...
% ls /usr/share/zoneinfo/America/|wc -l 144 % ls /usr/share/zoneinfo/Asia/|wc -l 99
Asia has around 59% of the world's population in 48 countries; the Americas have 14% in 35 countries. Seems quite possible there's scope to improve things in Asia.
Yes, Asia could split itself into more countries, for example.... Or perhaps Asian countries are not as crazy as Western Hemisphere countries about doing silly things with summer/daylight savings time rules: $ egrep '^Rule' northamerica southamerica | wc -l 610 $ egrep '^Rule' asia | wc -l 463 or about having multiple zones per country (China has two, the contiguous 48 states of the US has four plus various random places that don't do DST): $ egrep '^Zone' northamerica southamerica | wc -l 140 $ egrep '^Zone' asia | wc -l 61 I.e., having a lot of stuff in the tzdb for your continent could be considered a bug rather than a feature; that is *not* necessarily a sign that the tzdb doesn't do a good enough job of covering your continent, it may be just a sign that your continent doesn't impose as much of a burden on the tzdb....
On 2019-02-19 00:53, Guy Harris wrote:
On Feb 18, 2019, at 9:47 PM, Kevin Lyda <kevin@ie.suberic.net> wrote:
By populations... % ls /usr/share/zoneinfo/America/|wc -l 144 % ls /usr/share/zoneinfo/Asia/|wc -l 99 Asia has around 59% of the world's population in 48 countries; the Americas have 14% in 35 countries. Seems quite possible there's scope to improve things in Asia. Yes, Asia could split itself into more countries, for example.... Or perhaps Asian countries are not as crazy as Western Hemisphere countries about doing silly things with summer/daylight savings time rules: $ egrep '^Rule' northamerica southamerica | wc -l 610 $ egrep '^Rule' asia | wc -l 463 or about having multiple zones per country (China has two, the contiguous 48 states of the US has four plus various random places that don't do DST): $ egrep '^Zone' northamerica southamerica | wc -l 140 $ egrep '^Zone' asia | wc -l 61 I.e., having a lot of stuff in the tzdb for your continent could be considered a bug rather than a feature; that is *not* necessarily a sign that the tzdb doesn't do a good enough job of covering your continent, it may be just a sign that your continent doesn't impose as much of a burden on the tzdb....
...also the tzdb requires a documentary reference source for time zone history - someone to translate that into English - and post it to this list - finding the former - doing the latter - and posting it here - seems to be a barrier - perhaps due to language - perhaps lack of interest, involvement, skills to address the issue, or the combination thereof leading to finding this list? -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
Ho Chi Minh City and Hanoi are two separate big economic regions of Vietnam, just like Nick Phake said, creating two separate time zone names for the two regions is reasonable. You have also said that using Shanghai's time zone represents China, but then still creates timezones for Beijing. Vào 1:02, Th 2, 18 thg 2, 2019 KP <khaiphan9x@gmail.com đã viết:
These are the reasons that I think are reasonable - After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam - +7:00 (North Vietnam and All Vietnam since 1975) timezone has been the longest unified timezone ever, compared to Asia/Saigon, Asia/Ho_Chi_Minh (modified many times)
I would like to suggest adding a timezone for Hanoi or changing the name from Asia/Ho_Chi_Minh to Asia/Hanoi as the official timezone for Vietnam.
Having the same article should be considered
https://tz.iana.narkive.com/foJrvdQn/tz-patch-tzdata-asia-ha-noi-add-new-tim...
On Feb 17, 2019, at 8:22 PM, KP <khaiphan9x@gmail.com> wrote:
Ho Chi Minh City and Hanoi are two separate big economic regions of Vietnam, just like Nick Phake said, creating two separate time zone names for the two regions is reasonable.
Tzdb regions aren't created based on economic regions, they're created based on time zone offsets and standard/summer time rules; to quote the "Scope of the tz database" section of the theory document: The tz database attempts to record the history and predicted future of all computer-based clocks that track civil time. It organizes time zone and daylight saving time data by partitioning the world into timezones whose clocks all agree about timestamps that occur after the POSIX Epoch (1970-01-01 00:00:00 UTC). The database labels each timezone with a notable location and records all known clock transitions for that location. Although 1970 is a somewhat-arbitrary cutoff, there are significant challenges to moving the cutoff earlier even by a decade or two, due to the wide variety of local practices before computer timekeeping became prevalent. Each timezone typically corresponds to a geographical region that is smaller than a traditional time zone, because clocks in a timezone all agree after 1970 whereas a traditional time zone merely specifies current standard time. For example, applications that deal with current and future timestamps in the traditional North American mountain time zone can choose from the timezones America/Denver which observes US-style daylight saving time, America/Mazatlan which observes Mexican-style DST, and America/Phoenix which does not observe DST. Applications that also deal with past timestamps in the mountain time zone can choose from over a dozen timezones, such as America/Boise, America/Edmonton, andAmerica/Hermosillo, each of which currently uses mountain time but differs from other timezones for some timestamps after 1970. Clock transitions before 1970 are recorded for each timezone, because most systems support timestamps before 1970 and could misbehave if data entries were omitted for pre-1970 transitions. However, the database is not designed for and does not suffice for applications requiring accurate handling of all past times everywhere, as it would take far too much effort and guesswork to record all details of pre-1970 civil timekeeping. Although some information outside the scope of the database is collected in a file backzone that is distributed along with the database proper, this file is less reliable and does not necessarily follow database guidelines. so, according to what Phake Nick said: It is actually reasonable to have both Asia/Hanoi and Asia/Ho_Chi_Minh in tz database because the two cities (and the two fractions that control them) used different timezone from year 1968 to 1975, which mean even time after the UNIX Epoch would be affected. there would be two zones because, on dates since the POSIX Epoch, the two regions differed in their time zone.
You have also said that using Shanghai's time zone represents China, but then still creates timezones for Beijing.
I don't know who created a timezone for Beijing, but the tzdb doesn't do so, because there is no difference that we know of between Beijing and Shanghai and... in either offset-from-UTC or standard/summer time rules. There *is* a second tzdb region for China, Asia/Urumqi, which has an offset of +0600 from UTC, rather than the +0800 for the Asia/Shanghai zone for most of China, and which is always in standard time, unlike Asia/Shanghai, which had summer time rules from 1986 until 1991.
On 2019-02-17 21:22, KP wrote:
Vào 1:02, Th 2, 18 thg 2, 2019 KP đã viết:
These are the reasons that I think are reasonable - After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam - +7:00 (North Vietnam and All Vietnam since 1975) timezone has been the longest unified timezone ever, compared to Asia/Saigon, Asia/Ho_Chi_Minh (modified many times) I would like to suggest adding a timezone for Hanoi or changing the name from Asia/Ho_Chi_Minh to Asia/Hanoi as the official timezone for Vietnam. Having the same article should be considered https://tz.iana.narkive.com/foJrvdQn/tz-patch-tzdata-asia-ha-noi-add-new-tim...
Ho Chi Minh City and Hanoi are two separate big economic regions of Vietnam, just like Nick Phake said, creating two separate time zone names for the two regions is reasonable. You have also said that using Shanghai's time zone represents China, but then still creates timezones for Beijing.
If you see any timezone locations for Beijing, please talk to your software vendor about adding the locations you desire, as Beijing is not in the tzdb. Whether the locations you desire map internally to Asia/Bangkok, Asia/Ho_Chi_Minh, or Asia/Saigon will make no difference to the time displayed on your system. If you need correct times prior to 1970, please consider submitting patches referencing your research sources against the appropriate backzones, possibly being prepared to maintain your own backzones if not accepted in tzdb. This may be easier if you create your own fork of the experimental github repo and test making your patches against that, building tzdb files matching your requirements, possibly including backzones. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised.
On 2019-02-17 18:02, KP wrote:
These are the reasons that I think are reasonable - After merging with Ha Tay, Hanoi (capital) is the largest province in Vietnam - +7:00 (North Vietnam and All Vietnam since 1975) timezone has been the longest unified timezone ever, compared to Asia/Saigon, Asia/Ho_Chi_Minh (modified many times)
What I find more disturbing is the following: The tzdb "time zone" Asia/Hanoi in backzone/ gives reliable historical detail before 1970. But tzdb data do not give any clue which "time zone" can be used for it when the historical detail is not needed, because there is no link from Asia/Hanoi to Asia/Bangkok. I would find such a link helpful, at least for the connaisseurs of historical timestamps. As far as I can see, this is the only case where there is a name in backzone/ that does not occur as a link in the remaining data. Michael Deckers.
On 2/18/19 7:56 AM, Michael H Deckers via tz wrote:
this is the only case where there is a name in backzone/ that does not occur as a link in the remaining data.
Yes, that's correct. The 'backzone' file mostly holds data I created long ago that was later determined to be out of scope for tzdb, and so moved to 'backzone' with Link lines left behind for backward-compatibility reasons. Once that was done, there has been little motivation to create more 'backzone' entries, they're out of scope. The only exception so far has been Hanoi, as I later got high-quality data for Vietnam from Trần's book that was useful for improving Asia/Ho_Chi_Minh, and puzzling the data out gave an entry for Hanoi that seemed worth recording in 'backzone' even though it's out of scope. This exception doesn't need a backward-compatibility link, since there's nothing to be backward-compatible to.
participants (13)
-
Brian Inglis -
Clive D.W. Feather -
Guy Harris -
Hans-Joerg Happel -
Kevin Lyda -
KP -
Lester Caine -
Michael H Deckers -
Paul Eggert -
Phake Nick -
Robert Elz -
Steve Allen -
Tim Parenti